1. Field of the Invention
The present invention relates generally to a system for monitoring repeaters in a span line; and more particularly, to a system for in-service monitoring of repeater bipolar violations for a T1 span line.
2. Description of the Prior Art
T1 spans have been known in the art for more than 20 years and typically connect together two remote communication points. A T1 span has span lines connected by regenerative repeaters that are each normally spaced about every mile or so in the T1 span. The regenerative repeaters perform various function to a T1 span signal being transmitted over the T1 span, including equalization, clock recovery, pulse detection, and regenerative transmission. One problem in the art is that the regenerative repeaters break down at remote locations along the T1 span causing data errors.
Current T1 spans use smart or intelligent regenerative repeaters that are well known in the art, such as the Txport STARS (span test and restoral system). The smart regenerative repeaters have built-in detection circuits, for providing continuous performance monitoring to each node in the span, as described in Telephony, Jun. 15, 1992. The built-in detection circuit may include a bipolar violation detection circuit. However, one major disadvantage of the known T1 spans is that the central office which monitors the T1 span does not receive automatic error detection information from the smart or intelligent regenerative repeaters.
Another major disadvantage of the known T1 spans is that service technicians have to query each repeater to evaluate error detection information in the built-in detection circuits in order to perform fault isolation, which is costly and time-consuming.
Still another major disadvantage of the known T1 spans is that error detection information cannot be obtained while the T1 span is in-service, except for spans using an Extended Super Frame (ESF) datalink. Thus, in order to isolate a fault in a repeater along the T1 span, the T1 span must be taken out of service. Out-of-service fault isolation and maintenance is very expensive because the customer dictates when the T1 span can be worked on and the cost in man/hours escalates if the work needs to be done at night during low traffic hours.